High Wind in Oregon, November 22 to 23, 2018

Area Forecast Discussion
National Weather Service Medford OR
300 AM PST Thu Nov 22 2018

.DISCUSSION...22/00Z NAM/GFS/EC in.

A long wave trough remains offshore near 130W with southwest flow
aloft over the Pacific Northwest. The area remains vulnerable to
fronts associated with short waves ejecting from the low.

One such wave moved onshore Wednesday, bringing precipitation and
wind to the area. The strongest of the string will move onshore
Thursday. This one will generate a closed low at the surface with
a tight gradient and will likely produce storm force winds over
the coastal waters and high winds along the coast with gusts
possibly exceeding 70 mph at capes, headlands and other exposed
areas. The ridges, Shasta Valley, and the east side will also see
strong winds. See NPWMFR for details on the strength and timing of
the winds.

Another round of moderate to heavy rainfall will develop later
today, arriving at the coast 7-9 am, then spreading inland. A
period of gusty winds may precede the rainfall again in the Rogue
Valley, but the rain will start late this morning and continue
through the afternoon. Steady precipitation will push east of the
Cascades this afternoon. Snow levels will remain around 5000
feet, wavering 500 feet either side of that. This will bring
significant snow to the mountains. See WSWMFR for forecast
amounts, snow levels, and timing.

A break in the action will occur Thursday evening, but yet
another Pacific storm system will roll in late Thursday night into
Friday. This one is a warm front and snow levels will rise as it
moves through, perhaps moving above 7000 feet Friday.
Precipitation will be heavy in some areas, and there is the
potential for flash flooding or debris flows on recent burn areas.
Details can be found in FFAMFR, which includes a Flash Flood
Watch for the burn areas.

The upper trough will finally move onshore Friday. A long wave
ridge will build into the west coast behind it. This will bring
drier weather Saturday.

Long term discussion from the Wednesday afternoon AFD...Sunday
through Wednesday Night. Although upper level ridging will be in
place over the region Sunday, the models are depicting a weak wave
traversing through the ridge. This little impulse, although not
expected to be a major player in the weather scheme, should
provide enough lift and moist onshore flow to produce light
showers along the coast and the Cascades north of Crater Lake.

The next major front to reach the area is now expected to arrive
Monday night into Tuesday. There are some differences between the
model suites, mainly in regard to the surface features. The
operational ECMWF brings a surface low onshore well to the north of
Seattle. Meanwhile, the GFS solution brings a rapidly deepening low
onshore near the mouth of the Columbia River. These two scenarios
present vastly different wind regimes, but both should produce
plenty of rainfall. As a result, there is more than enough
confidence on precipitation to keep rather high chances in the
forecast for monday night through Tuesday night. Confidence in the
wind forecast remains pretty low, so have kept them on the weaker
side for now.

Beyond Tuesday, there is little agreement between the models, except
that nearly all suites keep the wet and active pattern going, with
moist onshore flow and numerous troughs and fronts on deck to push
through our region. Have kept the remainder of the forecast wet and
active, but will not attempt to nail down details until there is
less uncertainty on the timing and strength of the individual
features. -BPN

&&

.AVIATION...For the 22/12Z TAFs...IFR/LIFR conditions are present,
mainly for inland west side valleys where recent rainfall has
provided ample moisture for fog to develop. Elsewhere a mix of
IFR/MVFR conditions exist. The lower conditions may temporarily
improve during the next few hours as showers continue to move
through the area, however, expect the prevailing conditions to be on
the lower end of flight rules. Terrain will be obscured throughout
the TAF period.

Later this morning, the attention turns to a powerful front expected
to move through the area today. Strong gusty winds will be the main
concern with this front, especially along the coast, east of the
Cascades and in the Shasta Valley. While it will be breezy
everywhere later this morning and afternoon, it may take some time
for the stronger winds aloft to surface in the more sheltered
valleys. This will lead to LLWS concerns for inland valleys west of
the Cascades, including KMFR and KRBG. Expect a mix of VFR/MVFR
conditions, with possible IFR/LIFR conditions in heavy rain as this
front moves through later this morning and into the afternoon. /BR-y

&&

.MARINE...Updated 145 AM PST Thursday 22 November 2018...Conditions
will significantly worsen as the morning progresses today. The
strongest in a series of fronts will arrive early this morning,
bringing heavy rain, strong southerly gales and an area of sustained
storm force winds. These storm force winds are expected from 5 nm to
25 nm from shore from Cape Sebastian northward. Very steep and
dangerous wind driven seas are expected in response to these strong
winds late this morning through this evening. These very steep seas
will subside some overnight, but remain elevated as a mix of fresh
swell combines with building west swell.

Winds will ease briefly later this evening, but another low pressure
is expected to move into the area late tonight into Friday. This
system will be weaker, and quicker to move through, but may bring
another round of gales and very steep seas to the waters late
tonight into Friday morning. Have issued a Gale Watch to cover this
as the exact location of the gales is still uncertain.

Winds will ease Friday night into Saturday, but seas will remain
elevated due to a mix of west and southwest swell. There will be a
brief break in the weather on Saturday, but another, even weaker
front is expected early Sunday morning. The active pattern is
expected to continue through next week with several more fronts
expected. /BR-y

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory from 10 AM this morning to 4 AM PST
        Friday for ORZ029>031.
     Wind Advisory from 10 AM this morning to 7 PM PST Friday for
        ORZ030-031.
     Winter Storm Warning from 10 AM this morning to 4 AM PST Friday
        for ORZ030-031.
     High Wind Warning from 10 AM this morning to 4 AM PST Friday for
        ORZ031.
     Gale Watch from late tonight through Friday morning for ORZ021.
     Winter Weather Advisory from 10 AM this morning to 4 AM PST
        Friday above 4500 feet in the for ORZ027-028.
     Winter Storm Warning from 10 AM this morning to 4 AM PST Friday
        above 5500 feet in the for ORZ027-028.
     High Wind Warning from 7 AM this morning to 4 PM PST this
        afternoon for ORZ021-022.
     Flash Flood Watch from 10 AM PST this morning through Friday
        afternoon for ORZ022-024.
     Wind Advisory from 10 AM this morning to 4 AM PST Friday for
        ORZ029.

CA...Wind Advisory from 10 AM this morning to 7 PM PST Friday for
        CAZ085.
     Winter Storm Warning from 10 AM this morning to 4 AM PST Friday
        above 4500 feet in the for CAZ080.
     Wind Advisory from 10 AM this morning to 4 AM PST Friday for
        CAZ084.
     Winter Storm Warning from 10 AM this morning to 4 AM PST Friday
        above 5000 feet in the for CAZ082-083.
     Flash Flood Watch from 10 AM PST this morning through Friday
        afternoon for CAZ080.
     High Wind Warning from 7 AM this morning to 10 AM PST Friday for
        CAZ081.
     Wind Advisory until 10 AM PST Friday for CAZ081.
     Winter Weather Advisory from 10 AM this morning to 4 AM PST
        Friday for CAZ085.

Pacific Coastal Waters...Gale Watch from late tonight through Friday
        morning for PZZ350-356-370-376.
     Small Craft Advisory until 4 AM PST early this morning for
        PZZ350-356-370-376.
     Storm Warning until 1 PM PST this afternoon for
        PZZ350-356-370-376.
     Gale Warning until 1 PM PST this afternoon for
        PZZ350-356-370-376.
     Hazardous Seas Warning from 1 PM this afternoon to 10 AM PST
        Friday for PZZ350-356-370-376.

15/15/03

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
801 AM PST THU NOV 22 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0800 AM     HEAVY RAIN       6 E GOLD BEACH          42.42N 124.31W
11/22/2018  M2.11 INCH       CURRY              OR   TRAINED SPOTTER

0730 AM     HEAVY RAIN       SELMA                   42.28N 123.62W
11/22/2018  M1.85 INCH       JOSEPHINE          OR   TRAINED SPOTTER

0700 AM     HEAVY RAIN       2 N PROVOLT             42.32N 123.23W
11/22/2018  M0.56 INCH       JOSEPHINE          OR   TRAINED SPOTTER

&&